It took me 9 batches to get a sourdough starter that actually rises, and I almost quit at batch 6
I started trying to grow a sourdough starter back in March and it took until the first week of June before I got one that would double in size in 4 hours. The problem was my kitchen stays around 65 degrees, so every starter I made just sat there and got watery and smelled like nail polish remover. I tossed 6 jars down the drain because I thought they were dead. A baker named Rosa at the Saturday market in Boise finally asked me what temp my counter was and told me to stick the jar in my oven with just the light on. That got it to about 78 degrees and it took off in 3 days. I also switched from tap water to bottled because our city water is heavy on chlorine. Now I feed it once a day with 50g flour and 50g water and it bubbles up like clockwork. If your starter keeps stalling, what temp is your room actually sitting at? I bet that is your problem and not your flour.